Cord Jefferson extends Santorum's logic on abortion, from his comment that it's "remarkable for a black man [i.e. president Obama] to say, 'we're going to decide who are people and who are not people.'"
We assume Santorum is attempting, ham-fistedly, to compare abortion to something like the the three-fifths compromise, in which the government decided that black slaves were subhuman. But by that logic, Obama could be forced like a square peg into the round holes of every struggle. How receptive would we be to an argument that said, as someone of an ethnicity that was once compared to mules, Obama should empathize more with People for the Ethical Treatment of Animals?
Joe Klein, who agrees with Santorum on almost nothing, nevertheless defends him:
First, you must understand that Santorum truly believes that abortion is murder--at any point after conception, even when the mother's health is at risk (as it was in the case of one of his wife's pregnancies). This is an extreme position, but not an implausible one. If you believe that a fetus is a person, then abortion is the denial of its most basic right--the right to exist. According to Santorum, the only other category of Americans whose civil rights were so severely truncated were slaves. He's right about that. Slaves were considered property; there was also that most odious Constitutional assertion that, in terms of representation, blacks counted as 3/5s of a person. Santorum believes that this history should make the descendants of slaves more sensitive to the civil rights of fetuses. There are a great many members of the black church who would agree with him.
I agree with Joe. Santorum's embrace of very modern - and not traditional - Catholic doctrine on this makes his analogy internally consistent, if a little offensive. Using Obama's race against him, even when doing so to make a valid point, doesn't help much. I'd add, however, that there is an obvious difference in as much as slave-owners did not own those "slaves" within their own bodies. Women do. And the defense of the freedom of that woman to do with her body as she sees fit is far more complicated than ending plantations.